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Learning Outcomes in Listing:
i. Describe the lock and key model of enzyme action.
ii. Explain the induced fit model of enzyme action.
iii. Compare and contrast the lock and key model with the induced fit model.
Summary of Lesson:
Enzymes are biological catalysts that speed up chemical reactions in the body by lowering activation energy. The precise manner in which enzymes bind to substrates and catalyze reactions has been explained through two main models: the lock and key model and the induced fit model. This lesson will break down these models to provide a clear understanding of enzyme action.
i. Lock and Key Model:
Proposed by Emil Fischer, it suggests that the enzyme's active site (the lock) is perfectly shaped to fit a specific substrate (the key).
This model emphasizes the specificity of enzymes, implying that each enzyme can only catalyze a reaction with a particular substrate that fits into its active site.
ii. Induced Fit Model:
Proposed by Daniel Koshland, this model suggests that while the active site of the enzyme is suited to the substrate, it is not a perfect fit.
Instead, the binding of the substrate induces a change in the shape of the enzyme, enhancing the fit and allowing the reaction to occur more efficiently.
This model accounts for the flexibility of enzymes and explains why certain enzymes can act on a range of similar substrates.
List of Important Questions for Self-Study:
i. What are the key features of the lock and key model of enzyme action?
ii. How does the induced fit model of enzyme action differ from the lock and key model?
iii. Why is specificity important in enzyme-substrate interactions?
iv. How do changes in the enzyme's structure during substrate binding affect the reaction?
v. Can one enzyme act on multiple substrates? How does the induced fit model explain this?
Important Terminologies Used in Lesson:
Enzyme: A protein that acts as a catalyst to speed up a chemical reaction.
Substrate: The molecule upon which an enzyme acts.
Active Site: The region on an enzyme where the substrate binds.
Lock and Key Model: A model for enzyme-substrate interaction suggesting that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.
Induced Fit Model: A model that describes how enzyme-substrate binding induces a conformational change in the enzyme, enhancing the fit between the enzyme and substrate.
